The present invention relates particularly to tire pressure measuring devices for trucks and heavy vehicles such as tractors for hauling semi-trailers. One of the biggest operating expenses for trucks is the cost of tires. With underinflated tires, the wear of tires is excessive, the fuel consumption increases, the handling characteristics of the vehicle are affected in a negative manner and the risk for catastrophic tire failure increases, and the road safety is jeopardized. With under inflation the tires get hot and the risk for thread separation increases especially in re-threaded tires.
While the U.S. government has ruled mandatory on all new cars and light trucks to have an incorporated Tire Pressure Monitoring Systems TPMS on the vehicles there is no current law for the heavy vehicles. Therefore only a small percentage of trucks have TPMS installed as original equipment. Although truck drivers are typically aware of the importance of having the right tire pressure, the amount of time and effort needed to properly inspect the tire pressure in all the tires often makes the driver neglect the inspection assuming that the pressure is correct. In addition to being time consuming on the typical dual wheel rear axles it is also inconvenient since it is often necessary to be down on your knees on the ground to locate valve stems to be able to check the pressure. A study, conducted by the United States Government, showed that 56% of all truck on the road in USA had one or more tire underinflated. U.S. Dept. of Commerce, National Technical Information Service, pub #PB2005100013, “Commercial Vehicle Tire Condition Sensors.” Research performed by Booz Allen Hamilton, Inc., McLean, Va.
Many of the aftermarket TPMS are difficult to use for the end user and to market for the distributors due to several reasons:                Tire location programming. Since most TPMS display only which tire is underinflated on the screen of the receiver, there is a need to program the system to read which transmitter is on which wheel. This is a time consuming and often confusing procedure for the common user and even for the vehicle maintenance personnel. Some TPMS have the transmitters preprogrammed at the factory which means a broken transmitter needs to be replaced with the right preprogrammed unit from the factory, and no spare units will be available required in inventory for the fleet.        Preset pressure ranges. Often the pressure warning threshold has been preset by the system manufacturer which means that for a fleet to purchase these devices they need to order units with the right warning threshold for each vehicle since the pressure differs from vehicle to vehicle and often differs depending on the axle the tire is mounted to. These systems make it difficult for the distributor to provide his customer with all the right pressure ranges in advance. However, many systems can be programmed for the warning threshold but by an often rather complicated series of inputs to the system.        Very few systems allow several monitors and a capability to cross monitor several vehicles which make those systems useless for maintenance and service personnel.        No systems are capable of monitoring a series of trailers waiting to be picked up by a tow vehicle such as a tractor.        
The intent with the present invention is to address inconvenience factors in checking the tire pressure and the shortcoming of other systems.